Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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672
FXUS64 KOUN 030337
AFDOUN

Area Forecast Discussion
National Weather Service Norman OK
937 PM CST Fri Dec 2 2016

.UPDATE...
Main update was to increase POPs.

&&

.DISCUSSION...
Widespread rain continues to spread northeast across the area.
Every mesonet station across the southwestern half of the forecast
area has measured rain and the precipitation area continues to
look solid in the short-term as it moves into central and
northern Oklahoma. Therefore have increased POPs to categorical
across most of the southwestern two-thirds of the area, and
increased POPs to likely almost everywhere. Temperatures in the
northwest have stayed up so far, but those will begin to fall as
the precipitation spreads into that area with airmass cooling and
dewpoints rising with the precipitation. The temperature and even
wet bulb temperatures across far northwest Oklahoma looks like it
should remain above 32 so frozen precipitation looks unlikely in
our forecast area. Forecast min temperatures still look
reasonable.

&&

.PREV DISCUSSION... /issued 509 PM CST Fri Dec 2 2016/

DISCUSSION...
Please see the 00Z aviation discussion below.

AVIATION...
Rain will continue to make its way out of TX from the SW this
evening. There is high confidence in at least MVFR cigs developing
over most terminals by sunrise...with even lower (IFR) cigs
expected shortly after that. Lightning strikes appear very
unlikely right now. Winds will remain east to southeast for most
of the forecast period.

PREV DISCUSSION... /issued 411 PM CST Fri Dec 2 2016/

DISCUSSION...
Primary forecast concern is focused on increasing rain chances
tonight through Saturday.

Currently, a dynamic 500 mb trough continues to dig east/southeast
across the southwestern U.S. From latest WV imagery, the trough
axis extends from the northern western high plains of WY/NE/SD to
the Gulf of California. Ahead of it, increasing moisture return
from both the Pacific and the Gulf of Mexico have combined to
result in increasing stratus through the day from the Rio Grande
Valley to Oklahoma. Additionally, isolated to scattered showers
have been developing off and on across portions of western north
Texas and southern Oklahoma, primarily in response to a weak 850mb
boundary and isentropic response around 310 and 315 K. RAP
soundings through the day have done an excellent job capturing
this feature.

With continued warm air advection ahead of the slowly approaching
500mb trough, profiles will continue to moisten through the low to
mid levels. In response, showers and rain chances will gradually
increase in coverage from western north Texas into Oklahoma through
the overnight hours into early Saturday. Overall, temperature
profiles in the low levels across the region will remain above
freezing. As with the previous forecasters (BRB/VM/MAD, etc.)
sticking towards the deterministic models for temperatures
although the blends have been catching on to the warmer trend.
Therefore expect precipitation to remain as rain overnight across
the region. However, across far northwestern Oklahoma, the RAP,
GFS, and ECMWF continue to show 0-5km show a weak warm nose of 1
to 3 C wet bulb temperatures, which would result in some partial
melting, but surface wet bulb temperatures are likely to remain
just above freezing. Therefore, kept the slight chance of snow,
but with higher chances for Rain. If any snow does develop, it
would pose no impacts to roads or visibility.

Widespread scattered rain will continue through Saturday as the
500mb trough continues to churn over western Mexico. The highest
rain chances will continue to slide to the east and southeast
overnight into Sunday. As the 500mb low begins to lift eastward
across Mexico into Monday morning, towards the lower Rio Grande
Valley, rain chances will persist across the Red River valley and
increase across southeastern Oklahoma before ending into early
Tuesday.

A colder, more winter-like pattern will emerge by midweek. A broad
trough will position itself over the central U.S. Still some
noticable differences between guidance suites of the
GFS/ECMWF/Canadian with the 500mb trough. The GFS remains about 8 to
12 hours faster than the ECMWF overall, with the ECMWF more
aggressive with the depth of the trough. This has made for a
tricky temperature and potential precipitation forecast for
Wednesday into Thursday. Similar to the night shift and similar to
the Canadian model, split the difference between the two.
Currently expecting some frosty temperatures, especially Wednesday
night into Thursday, where lows will dip into the lower teens
across northern Oklahoma to the upper teens to lower 20s toward
the Red River. Additionally, with the frontal passage Wednesday
afternoon/evening, some light snow may develop, with little to no
impacts to travel expected at this time as any snow will be
flurries to very light. The big impact will be strong north winds
which will result in overnight wind chills in the single digits
across northern and central Oklahoma Wednesday night.

Kurtz

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  43  46  38  53 /  90  80  50  10
Hobart OK         42  45  38  53 / 100  70  50  10
Wichita Falls TX  45  47  41  55 / 100  80  50  20
Gage OK           35  42  31  54 /  80  60  30   0
Ponca City OK     40  47  37  55 /  60  70  50  10
Durant OK         45  47  42  53 /  90 100  70  20

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&

$$



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